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A001111
Number of inequivalent Hadamard designs of order 4n.
1
1, 1, 1, 5, 6, 1106, 208310, 10374196953
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OFFSET
1,4
COMMENTS
In other words, number of 2-(4*n-1,2*n-1,n-1) symmetric designs.
LINKS
Table of n, a(n) for n=1..8.
R. K. Guy,
Letters to N. J. A. Sloane, June-August 1968
.
Edward Spence,
Hadamard matrices
.
Edward Spence,
Classification of Hadamard matrices of order 24 and 28
, Discrete Math. 140 (1995), no. 1-3, 185-243.
Index entries for sequences related to Hadamard matrices
CROSSREFS
Sequence in context:
A246307
A269588
A048658
*
A374961
A355022
A133079
Adjacent sequences:
A001108
A001109
A001110
*
A001112
A001113
A001114
KEYWORD
nonn
,
hard
,
nice
,
more
AUTHOR
N. J. A. Sloane
EXTENSIONS
a(8) from
Brendan McKay
, Feb 11 2012
STATUS
approved
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Last modified August 28 23:11 EDT 2024. Contains 375508 sequences. (Running on oeis4.)